In the dental arts tooth crown and bridge caps are cemented securely and firmly onto one or more shaped stubs for support. On some occasions it becomes necessary to remove the caps for dental work, such as if caries develop under the caps or if the cap becomes partly loosened. In the prior art it has been very difficult to remove caps non-destructively. If caps are ceramic they are readily fractured. If they involve even more expensive bridges, they can be broken or twisted requiring significant rework.
Typical prior art tools and methods for dental cap removal include the following U.S. patents:
S. R. Sykes U.S. Pat. No. 2,428,689 Oct. 7, 1947 PA1 D. J. Wilson U.S. Pat. No. 3,755,901 Sept. 4, 1973 PA1 J. A. West U.S. Pat. No. 1,109,096 Sept. 1, 1914 PA1 G. J. Lozano et al. U.S. Pat. No. 3,690,006 Sept. 12, 1972 PA1 C. C. Reed Jr. U.S. Pat. No. 3,579,834 May 25, 1971
All of these patents involve clamps for engaging and holding the caps in order to pull them off. These clamps however have a tendancy to slip off, to fracture ceramic caps or to bend, strain and twist bridgework. Furthermore, there is considerable shear force exerted on the cap and/or tooth stub by many of these prior art tools and methods that tend to damage the caps and or tooth stubs and cause patient pain and discomfort in the removal process. Also some of the tools are either so delicate because of limited space that they are not strong or they conversely take up so much room that they cannot be used in the limited work space available in the mouth.
An undercutting method and tool in G. W. Anderson U.S. Pat. No. 4,179,816 Dec. 25, 1979 has been proposed for insertion under a crown to force the crown off by pressure on small thin cap surface area. This method and tool cannot be used with permanently cemented caps having high adhering forces without rupturing the cap without removal. Also this method is not feasible for use to remove bridgework.
Similarly the custom made gripping jaw surface of A. M. Zatkin U.S. Pat. No. 3,889,376 June 17, 1975 is strictly for crowns and takes up so much room that it is difficult to use in the limited space available. It is also only feasible for symmetrical type crown usage without providing significant shear forces that tend to fracture the crown and cause tooth stub damage and patient discomfort. Limited contact is made with the crown on diametrically opposed sides which cause problems of balance, grasping area and limitation to crown shape.
Thus, this invention proposes to improve the state of the art by curing the defects of prior art cap removal methods and tools including those above identified. There is provided simple, universal means and methods of removing both crown and bridge cap structure without significant shear forces compatible with very limited work space in a mouth and the various configurations of caps that might be encountered.
Other features, advantages and structural distinctions will be made apparent throughout the following description, drawings and claims.